The present invention relates to magnetic hard disk drives. More specifically, the present invention relates to a method of connecting the micro-actuator to the driver arm suspension.
In the art today, different methods are utilized to improve recording density of hard disk drives. FIG. 1 provides an illustration of a typical drive arm configured to read from and write to a magnetic hard disk. Typically, voice-coil motors (VCM) 102 are used for controlling a hard drive's arm 104 motion across a magnetic hard disk 106. Because of the inherent tolerance (dynamic play) that exists in the placement of a recording head 108 by a VCM 102 alone, micro-actuators 110 are now being utilized to ‘fine-tune’ head 108 placement. A VCM 102 is utilized for course adjustment and the micro-actuator then corrects the placement on a much smaller scale to compensate for the VCM's 102 (with the arm 104) tolerance. This enables a smaller recordable track width, increasing the ‘tracks per inch’ (TPI) value of the hard drive (increased drive density).
FIG. 2 provides an illustration of a micro-actuator as used in the art. Typically, a slider 202 (containing a read/write magnetic head; not shown) is utilized for maintaining a prescribed flying height above the disk surface 106 (See FIG. 1). Micro-actuators may have flexible beams 204 connecting a support device 206 to a slider containment unit 208 enabling slider 202 motion independent of the drive arm 104 (See FIG. 1). An electromagnetic assembly or an electromagnetic/ferromagnetic assembly (not shown) may be utilized to provide minute adjustments in orientation/location of the slider/head 202 with respect to the arm 104 (See FIG. 1).
The physical and electrical coupling of a hard disk micro-actuator and magnetic head to a drive arm suspension can be difficult due to the environment within which it must operate. Using silver paste (high mercury-content epoxy) for physical/electrical attachment has drawbacks due to the viscous nature of epoxy under changing temperature and humidity. Under certain temperature and humidity conditions, the epoxy can deform, affecting the position of the slider and micro-actuator in relation to the suspension arm. Additionally, silver ions or silver atoms in the silver paste may begin to migrate from the epoxy to the micro-actuator, affecting the performance of the micro-actuator. While other options for bonding the actuator to the suspension arm exist, such as gold ball bonding (GBB) and solder bump bonding (SBB), the rigidity of these options can lead to greater damage. In particular, the thinness of the piezoelectric transducer (PZT) surface layer of the micro-actuator can reduce the peel strength between the PZT layer and the bonding pad, causing the connection to crack and create an electrical short between the two. It is therefore desirable to support the micro-actuator and connect it to the suspension arm using a method that can create strong a connection without the risks of deformation.